Receiving unit, receiving method and semiconductor device

ABSTRACT

A receiving unit, receiving method, and semiconductor device that reduce the size of circuits in a receiving unit. A receiving section receives signals sent from a base station and transmitted through a plurality of paths. A path tracking section detects timing of each of the plurality of paths through which the signals received by the receiving section were transmitted. A demodulating section demodulates the received signals by performing a despreading process according to the timing of the plurality of paths detected by the path tracking section. A correlation value calculating section calculates a correlation value between the received signals and a spreading code. A destination selecting section provides output from the correlation value calculating section to the path tracking section in the case of performing a path tracking process by the path tracking section and provides output from the correlation value calculating section to the demodulating section in the case of demodulating the received signals by the demodulating section.

BACKGROUND OF THE INVENTION

[0001] (1) Field of the Invention

[0002] This invention relates to a receiving unit, receiving method, andsemiconductor device and, more particularly, to a receiving unit andmethod for receiving and demodulating signals sent from a base stationand a semiconductor device for processing signals sent from a basestation.

[0003] (2) Description of the Related Art

[0004] With the wideband code division multiple access (W-CDMA)communication system, for example, signals to be sent are spread by theuse of a spreading code and then are sent. A mobile station selectsoptimum path timing for data it receives and performs despreading,synchronous detection, and RAKE combining. As a result, data will beobtained.

[0005] After initial synchronization, usually path timing needs to betracked frequently with a change of channel due to, for example,movement. A mobile station therefore includes a path tracking sectionfor monitoring the timing of a path for a receiving channel.

[0006] In addition, with the W-CDMA communication system, handovercontrol for switching a base station with which a mobile stationcommunicates to the optimum one at any time even during receiving datais exercised in order to always realize stable communication even duringmoving at a high speed. Therefore, the level (signal-to-interferenceratio (SIR), for example) of received data which are sent from basestations around the one with which a mobile station is communicating nowmust also be monitored. As a result, despreading, synchronous detection,and level measurement must be performed not only on data from the basestation with which a mobile station is communicating now but also ondata from other base stations.

[0007]FIG. 8 shows a block diagram of a path tracking section and datademodulating section in a conventional receiving unit which adopts theW-CDMA communication system.

[0008] As shown in FIG. 8, a conventional receiving unit which adoptsthe W-CDMA communication system comprises an antenna 10, receivingcircuit 11, A/D converting circuit 12, path tracking section 20, datademodulating section 30, RAKE combining circuit 40, level measuringcircuit 41, and power value calculating circuit 42.

[0009] The antenna 10 acquires electronic waves sent from a basestation.

[0010] The receiving circuit 11 converts the electronic waves acquiredby the antenna 10 into the corresponding electrical signals.

[0011] The A/D converting circuit 12 converts the electrical signals(analog signals) output from the receiving circuit 11 into thecorresponding digital signals (hereinafter referred to as “receiveddata”) and outputs them.

[0012] The path tracking section 20 includes a correlation circuit 21,integrating circuit 22, power value calculating circuit 23, integratingcircuit 24, and path selecting circuit 25. The path tracking section 20selects a path of high power on the basis of the received signals andoutputs the timing of the path to the data demodulating section 30 aspath information.

[0013] The correlation circuit 21 calculates a correlation valueobtained from the received data supplied from the A/D converting circuit12 and a predetermined code, being a spreading code, and outputs it tothe integrating circuit 22.

[0014] The integrating circuit 22 integrates the data output from thecorrelation circuit 21 by the slot and outputs the result obtained.

[0015] The power value calculating circuit 23 calculates the geometricmean of the data output from the integrating circuit 22 and outputs it.

[0016] The integrating circuit 24 integrates the output from the powervalue calculating circuit 23 by the frame and outputs the resultobtained.

[0017] The path selecting circuit 25 monitors the data output from theintegrating circuit 24, selects several paths in descending order ofpower value, and outputs their timing as path information.

[0018] The data demodulating section 30 includes operating sections 31-1through 31-n, a memory 32, a synchronous detection circuit 33, and achannel estimation circuit 34. The data demodulating section 30 operatesa correlation value obtained from a spreading code and received dataaccording to path information, performs synchronous detection, andoutputs the original data.

[0019] The operating section 31-1 includes a correlation circuit 31-1 aand code generating circuit 31-1 b. The correlation circuit 31-1 aoperates a correlation value obtained from received data and a spreadingcode supplied from the code generating circuit 31-1 b with timingcorresponding to path information supplied from the path selectingcircuit 25 and outputs the result.

[0020] The structure of the operating sections 31-2 through 31-n is thesame as that of the operating section 31-1, so descriptions of them willbe omitted.

[0021] The memory 32 stores data output from the operating sections 31-1through 31-n in predetermined areas.

[0022] The synchronous detection circuit 33 performs synchronousdetection on the data stored in the memory 32 and outputs the originaldata.

[0023] The channel estimation circuit 34 integrates the data stored inthe memory 32 by the frame and outputs the result.

[0024] The RAKE combining circuit 40 causes the time and phases ofsignals according to paths, which the synchronous detection circuit 33separated by despreading and output, to match, combines the signals, andoutputs the result.

[0025] The level measuring circuit 41 measures the level of the dataoutput from the RAKE combining circuit 40.

[0026] The power value calculating circuit 42 calculates the geometricmean of the data output from the channel estimation circuit 34 andprovides it to the level measuring circuit 41.

[0027] Now, the operation of the above conventional receiving unit willbe described.

[0028] The antenna 10 acquires electronic waves sent from a base stationand provides them to the receiving circuit 11.

[0029] The receiving circuit 11 converts the electronic waves acquiredby the antenna 10 into the corresponding electrical signals and outputsthem.

[0030] The A/D converting circuit 12 converts the electrical signals(analog signals) supplied from the receiving circuit 11 into thecorresponding digital signals and provides them to the path trackingsection 20 and data demodulating section 30.

[0031] The correlation circuit 21 calculates a correlation valueobtained from the received data supplied from the A/D converting circuit12 and a spreading code supplied from another block (not shown) whichcorresponds to the base station electronic waves from which are beingreceived by the antenna 10, and outputs it.

[0032] The integrating circuit 22 integrates the data output from thecorrelation circuit 21 by the slot and outputs the result.

[0033] The power value calculating circuit 23 calculates the geometricmean of the data which the integrating circuit 0.22 calculated byintegrating by the slot, and outputs it as data indicative of the powerof the received signals.

[0034] The integrating circuit 24 integrates the data output from thepower value calculating circuit 23 by the frame (a “frame” is greaterthan a “slot”) and outputs the result.

[0035] The path selecting circuit 25 refers to the data output from theintegrating circuit 24, selects several (n, in this example) paths indescending order of power of received signal, and outputs their timingas path information.

[0036] Each of the operating sections 31-1 through 31-n in the datademodulating section 30 operates a correlation value obtained from aspreading code supplied from a code generating circuit and the receiveddata supplied from the A/D converting circuit 12 in synchronization withtiming shown by the path information supplied from the path selectingcircuit 25 and outputs it.

[0037] The memory 32 stores the data output from the operating sections31-1 through 31-n in predetermined areas.

[0038] The channel estimation circuit 34 integrates one slot of a pilotsignal (reference signal), generates a signal indicative of the state ofa transmission line (channel), and provides it to the synchronousdetection circuit 33 and power value calculating circuit 42.

[0039] The RAKE combining circuit 40 causes the time and phases ofsignals according to paths, which the synchronous detection circuit 33separated by despreading and output, to match, combines the signals, andoutputs the result.

[0040] The level measuring circuit 41 measures the level of the dataoutput from the RAKE combining circuit 40.

[0041] The power value calculating circuit 42 calculates the geometricmean of the data output from the channel estimation circuit 34 andprovides it to the level measuring circuit 41.

[0042] However, the conventional receiving unit described above includesthe correlation circuit 21 and correlation circuits 31-1 a through31-na, that is to say, (n+1) correlation circuits. This will lead tolarge-scale circuits because correlation circuits usually need a largecircuit area.

SUMMARY OF THE INVENTION

[0043] The present invention was made under the background circumstancesas described above. An object of the present invention is to provide areceiving unit in which the scale of circuits can be reduced.

[0044] In order to achieve the above object, a receiving unit forreceiving and demodulating signals sent from a base station is provided.This receiving unit comprises receiving means for receiving signals sentfrom the base station and transmitted through a plurality of paths, pathtracking means for detecting timing of each of the plurality of pathsthrough which the signals received by the receiving means weretransmitted, demodulating means for demodulating the received signals byperforming a despreading process according to the timing of theplurality of paths detected by the path tracking means, correlationvalue calculating means for calculating a correlation value between thereceived signals and a spreading code, and destination selecting meansfor providing output from the correlation value calculating means to thepath tracking means in the case of performing a path tracking process bythe path tracking means and for providing output from the correlationvalue calculating means to the demodulating means in the case ofdemodulating the received signals by the demodulating means.

[0045] The above and other objects, features and advantages of thepresent invention will become apparent from the following descriptionwhen taken in conjunction with the accompanying drawings whichillustrate preferred embodiments of the present invention by way ofexample.

BRIEF DESCRIPTION OF THE DRAWINGS

[0046]FIG. 1 is a view for describing the operative principles of thepresent invention.

[0047]FIG. 2 is a block diagram for describing the structure of a firstembodiment of the present invention.

[0048]FIG. 3 is a block diagram showing in detail an example of thestructure of the correlation circuit shown in FIG. 2.

[0049]FIG. 4 is a view showing another example of the structure of thecorrelation circuit.

[0050]FIG. 5 is a flow chart for describing an example of a processperformed in the embodiment shown in FIG. 2.

[0051]FIG. 6 is a block diagram for describing the structure of a secondembodiment of the present invention.

[0052]FIG. 7 is a block diagram for describing the structure of a thirdembodiment of the present invention.

[0053]FIG. 8 is a block diagram for describing the structure of aconventional receiving unit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] Embodiments of the present invention will now be described withreference to the drawings.

[0055]FIG. 1 is a view for describing the operative principles of thepresent invention.

[0056] As shown in FIG. 1, a receiving unit according to the presentinvention comprises an antenna 1, receiving means 2, correlation valuecalculating means 3, destination selecting means 4, path tracking means5, demodulating means 6, and level measuring means 7.

[0057] The receiving means 2 receives signals via the antenna 1 whichwere sent from a base station and were transmitted through a pluralityof paths.

[0058] The path tracking means 5 detects the timing of each of pathsthrough which signals received by the receiving means 2 weretransmitted.

[0059] The demodulating means 6 demodulates received signals byperforming a despreading process according to the timing of a pluralityof paths detected by the path tracking means 5.

[0060] The correlation value calculating means 3 calculates acorrelation value between received signals and a spreading code.

[0061] The destination selecting means 4 provides output from thecorrelation value calculating means 3 to the path tracking means 5 inthe case of performing a path tracking process by the path trackingmeans 5 and provides output from the correlation value calculating means3 to the demodulating means 6 in the case of demodulating receivedsignals by the demodulating means 6.

[0062] The level measuring means 7 refers to signals demodulated by thedemodulating means 6 and measures the level of received signals.

[0063] Now, operation in FIG. 1 will be described.

[0064] The receiving means 2 receives electronic waves sent from a basestation via the antenna 1 and converts them into the correspondingelectrical signals.

[0065] The correlation value calculating means 3 calculates acorrelation value between the received signals supplied from thereceiving means 2 and a spreading code and provides it to thedestination selecting means 4. Spreading codes differ among basestations, so a spreading code for the base station with which thereceiving unit is communicating now is provided to the correlation valuecalculating means 3 and is stored there.

[0066] When communication is begun between the receiving unit and apredetermined base station, first the destination selecting means 4provides the results, being data, to the path tracking means 5.

[0067] As a result, the path tracking means 5 selects several from amongthe received signals transmitted through a plurality of paths indescending order of power and provides their timing to the demodulatingmeans 6 as path information.

[0068] The demodulating means 6 demodulates the data supplied from thecorrelation value calculating means 3 on the basis of the pathinformation supplied from the path tracking means 5 and provides theresults to the level measuring means 7.

[0069] The level measuring means 7 measures the level of the signalssupplied from the demodulating means 6.

[0070] The path tracking means 5 needs to perform a path trackingprocess only in a predetermined cycle (every fifty milliseconds, forexample), so the output from the correlation value calculating means 3can be provided to the demodulating means 6 during the remaining time.

[0071] The present invention therefore makes it possible to share thecorrelation value calculating means 3. As a result, the size of circuitscan be reduced.

[0072] When a base station with which the receiving unit communicateschanges, the destination selecting means 4 provides a correlation valueto the path tracking means 5 to make it perform a path tracking process.In this case, a path tracking process will not be performed in the abovepredetermined cycle.

[0073] Embodiments of the present invention will now be described.

[0074]FIG. 2 is a view showing the structure of a first embodiment ofthe present invention. As shown in FIG. 2, a receiving unit according tothe present invention comprises an antenna 10, receiving circuit 11, A/Dconverting circuit 12, path tracking section 20, data demodulatingsection 30, RAKE combining circuit 40, level measuring circuit 41, andpower value calculating circuit 42.

[0075] The antenna 10 acquires electronic waves sent from a basestation.

[0076] The receiving circuit 11 converts the electronic waves acquiredby the antenna 10 into the corresponding electrical signals.

[0077] The A/D converting circuit 12 converts the electrical signals(analog signals) output from the receiving circuit 11 into thecorresponding digital signals and outputs them.

[0078] The path tracking section 20 includes a correlation circuit 21,integrating circuit 22, power value calculating circuit 23, integratingcircuit 24, and path selecting circuit 25. The path tracking section 20selects a path of high power on the basis of received signals andoutputs it to the data demodulating section 30 as path information.

[0079] The correlation circuit 21 calculates a correlation valueobtained from the received data supplied from the A/D converting circuit12 and a predetermined code, being a spreading code, and outputs it tothe integrating circuit 22.

[0080]FIG. 3 is a view showing in detail an example of the structure ofthe correlation circuit 21.

[0081] As shown in FIG. 3, the correlation circuit 21 includesflip-flops (FFs) 80-1 through 80-N, FFs 81-1 through 81-N, multiplyingcircuits 82-1 through 82-N, and an adding circuit 83.

[0082] Received data output from the A/D converting circuit 12 is inputto the FF 80-1 and is transferred in turn to the next FF insynchronization with a clock signal supplied from a clock generatingcircuit (not shown). As a result, the received data will be delayedaccording to the cycle of a clock signal and be transferred in turn fromthe FF 80-1 to the FF 80-N.

[0083] A code, being a spreading code, is input to the FFs 81-1 through81-N. If the entire code has been input, the supply of a clock isstopped and the input data is held. The FFs 81-1 through 81-N differfrom the FFs 80-1 through 80-N in this respect.

[0084] The multiplying circuit 82-1 multiplies data supplied from the FF80-1 and data supplied from the FF 81-1 together and outputs the resultobtained. This is the same with the multiplying circuits 82-2 through82-N.

[0085] The adding circuit 83 operates the sum total of data output fromthe multiplying circuits 82-1 through 82N and outputs it.

[0086] As a result, a correlation value obtained from the received dataand spreading code will be output from the adding circuit 83.

[0087] The correlation circuit 21 described above is what is called a‘matched filter.’ By the way, a ‘sliding correlation circuit,’ like theone shown in FIG. 4, can also be used as a correlation circuit.

[0088] In this example, a sliding correlation circuit 70 includes a codegenerating circuit 71, multiplying circuit 72, adding circuit 73, and FF74. When a receiving timing signal is provided, the code generatingcircuit 71 begins to generate a spreading code and provides it to themultiplying circuit 72.

[0089] The multiplying circuit 72 multiplies received data and aspreading code together and outputs the result obtained.

[0090] The adding circuit 73 adds data output from the multiplyingcircuit 72 and the preceding data (despread data) output from the FF 74together and outputs the result.

[0091] The FF 74 temporarily stores data output from the adding circuit73, reads out the data it stores with the timing with which the nextdata will be output from the multiplying circuit 72, and provides it.

[0092] As a result, the FF 74 will output a correlation value obtainedfrom the received data and spreading code.

[0093] Compared with a matched filter, a sliding correlation circuit hasa simpler structure, but it operates a correlation value only withdetermined timing. That is to say, a matched filter operates acorrelation value obtained from received data input every moment and aspreading code and outputs it. In the present invention, thischaracteristic is used to enable the path tracking section 20 and datademodulating section 30 to share a correlation circuit.

[0094] Now, the describing of FIG. 2 will be resumed.

[0095] The integrating circuit 22 integrates data output from thecorrelation circuit 21 by the slot and outputs the result obtained.

[0096] The power value calculating circuit 23 calculates the geometricmean of data output from the integrating circuit 22 and outputs it.

[0097] The integrating circuit 24 integrates output from the power valuecalculating circuit 23 by the frame and outputs the result obtained.

[0098] The path selecting circuit 25 monitors data output from theintegrating circuit 24, selects several paths in descending order ofpower value, and outputs their timing as path information.

[0099] The data demodulating section 30 includes a selecting circuit 50,memory 32, synchronous detection circuit 33, and channel estimationcircuit 34. The data demodulating section 30 operates a correlationvalue obtained from a spreading code and received data according to pathinformation, performs synchronous detection, and outputs the originaldata.

[0100] The selecting circuit 50 selects data corresponding to pathsselected by the path selecting circuit 25 from output from thecorrelation circuit 21 and outputs it.

[0101] The memory 32 stores data output from the selecting circuit 50 inpredetermined areas.

[0102] The synchronous detection circuit 33 performs synchronousdetection on data stored in the memory 32 and outputs the original data.

[0103] The channel estimation circuit 34 integrates data stored in thememory 32 by the frame to generate a channel estimation signal andoutputs it.

[0104] The RAKE combining circuit 40 causes the time and phases of thesignals according to paths, which the synchronous detection circuit 33separated by despreading and output, to match, combines the signals, andoutputs the result.

[0105] The level measuring circuit 41 measures the level of data outputfrom the RAKE combining circuit 40.

[0106] The power value calculating circuit 42 calculates the geometricmean of data output from the channel estimation circuit 34 and providesit to the level measuring circuit 41.

[0107] Now, operation in the above embodiment will be described.

[0108] The antenna 10 acquires electronic waves sent from a base stationand provides them to the receiving circuit 11.

[0109] The receiving circuit 11 converts the electronic waves acquiredby the antenna 10 into the corresponding electrical signals and outputsthem.

[0110] The A/D converting circuit 12 converts the electrical signals(analog signals) supplied from the receiving circuit 11 into thecorresponding digital signals and provides them to the path trackingsection 20 and data demodulating section 30.

[0111] The correlation circuit 21 obtains a spreading code unique to abase station, with which the receiving unit is to communicate, fromanother block (not shown) and stores it in the FFs 81-1 through 81-N.When the A/D converting circuit 12 begins to provide the received datato the path tracking section 20, the received data is delayed insequence by the FFs 80-1 through 80-N. Output from the FFs 80-1 through80-N is provided to the multiplying circuits 82-1 through 82-Nrespectively.

[0112] The multiplying circuit 82-1 multiplies the received data outputfrom the FF 80-1 and the spreading code output from the FF 81-1 togetherand outputs the result obtained. The same applies to the multiplyingcircuits 82-2 through 82-N.

[0113] The adding circuit 83 operates the sum total of the data outputfrom the multiplying circuits 82-1 through 82-N and outputs it asdespread data.

[0114] The data output from the correlation circuit 21 is provided tothe integrating circuit 22. The integrating circuit 22 integrates oneslot of the data and outputs the result.

[0115] The power value calculating circuit 23 calculates the geometricmean of the data obtained as a result of the integrating circuit 22integrating by the slot and outputs it as data indicative of the powerof the received signal.

[0116] The integrating circuit 24 integrates the data output from thepower value calculating circuit 23 by the frame (a “frame” is greaterthan a “slot”) and outputs the result.

[0117] The path selecting circuit 25 refers to the data output from theintegrating circuit 24, selects several (n, in this example) paths indescending order of power of received signal, and outputs their timingas path information.

[0118] The path information output from the path selecting circuit 25 isprovided to the selecting circuit 50.

[0119] The selecting circuit 50 selects data corresponding to theseveral paths, which were selected in descending order of power ofreceived signal, from among the correlation values output from thecorrelation circuit 21 and provides it to the memory 32.

[0120] The blocks behind the correlation circuit 21 operate in apredetermined cycle or when a base station changes. At that point intime, the path selecting circuit 25 selects several paths in descendingorder of power of received signal and informs the selecting circuit 50of them.

[0121] The memory 32 stores the data selected by the selecting circuit50 in predetermined areas.

[0122] The channel estimation circuit 34 integrates one slot of a pilotsignal (reference signal), generates a signal indicative of the state ofa transmission line (channel), and provides it to the synchronousdetection circuit 33 and power value calculating circuit 42.

[0123] The RAKE combining circuit 40 causes the time and phases ofsignals according to paths, which the synchronous detection circuit 33separated by despreading and output, to match, combines the signals, andoutputs the result.

[0124] The level measuring circuit 41 measures the level of the dataoutput from the RAKE combining circuit 40.

[0125] The power value calculating circuit 42 calculates the geometricmean of the data output from the channel estimation circuit 34 andprovides it to the level measuring circuit 41.

[0126] This enables the path tracking section 20 and data demodulatingsection 30 to share the correlation circuit 21. As a result, the size ofcircuits can be reduced.

[0127] In the above embodiment, the selecting circuit 50 selects outputfrom the correlation circuit 21. However, another method may be adopted.For example, the entire data is stored in the memory 32 and only datacorresponding to output from the path selecting circuit 25 is read outfrom the memory 32.

[0128]FIG. 5 is a flow chart for describing the above operation. Thefollowing steps will be performed in compliance with this flow chart.

[0129] [Step S10] The correlation circuit 21 sets a code, being aspreading code, in the FFs 81-1 through 81-N.

[0130] [Step S11] The correlation circuit 21 provides received dataoutput from the A/D converting circuit 12 to the FFs 80-1 through 80-Nand calculates a correlation value obtained from the received data andspreading code.

[0131] [Step S12] The correlation circuit 21 provides a correlationvalue obtained by the operation to the path tracking section 20.

[0132] [Step S13] The path selecting circuit 25 provides pathinformation obtained by operating the output from the correlationcircuit 21 to the selecting circuit 50 in the data demodulating section30.

[0133] [Step S14] The correlation circuit 21 provides received dataoutput from the A/D converting circuit 12 to the FFs 80-1 through 80-Nand calculates a correlation value obtained from the received data andspreading code.

[0134] [Step S15] The correlation circuit 21 provides data obtained bythe operation to the selecting circuit 50 in the data demodulatingsection 30.

[0135] [Step S16] A control section (not shown) judges whether toterminate the process or not. If the control section does not terminatethe process, it proceeds to step S17. The control section terminates theprocess otherwise.

[0136] [Step S17] The control section (not shown) judges whether or notthe code, being the spreading code, corresponding to the base stationhas changed. If the code has changed, the control section proceeds tostep S18. If the code has not changed, the control section returns tostep S14 to repeat the same process.

[0137] [Step S18] The control section (not shown) judges whether toterminate the process or not. If the control section does not terminatethe process, it proceeds to step S10. The control section terminates theprocess otherwise.

[0138] This process will realize the function described above.

[0139] Now, a second embodiment of the present invention will bedescribed.

[0140]FIG. 6 is a block diagram showing the structure of the secondembodiment of the present invention. In FIG. 6, portions correspondingto those in FIG. 2 are expressed by the same symbols and descriptions ofthem will be omitted.

[0141] This embodiment differs from the first embodiment shown in FIG. 2in that the channel estimation circuit 34 is removed and that a memory60 to which output from the integrating circuit 22 is provided is added.Except for this, the structure of this embodiment is the same as that ofthe first embodiment.

[0142] The memory 60 temporarily stores data output from the integratingcircuit 22 and provides it to the synchronous detection circuit 33 andpower value calculating circuit 42.

[0143] The channel estimation circuit 34 shown in FIG. 2 performs theprocess of integrating one slot of data stored in the memory 32. Thisoperation is the same as that of the integrating circuit 22. That is tosay, the integrating circuit 22 can also be used as the channelestimation circuit 34. Therefore, in the second embodiment, the channelestimation circuit 34 is removed.

[0144] Operation in the second embodiment is the same as that in thefirst embodiment shown in FIG. 2, except that the integrating circuit 22integrates one slot of data for the channel estimation circuit 34.Detailed descriptions of it therefore will be omitted.

[0145] The above embodiment enables the path tracking section 20 anddata demodulating section 30 to share the integrating circuit 22. As aresult, the size of circuits can be reduced further.

[0146] Now, a third embodiment of the present invention will bedescribed.

[0147]FIG. 7 is a block diagram showing the structure of the thirdembodiment of the present invention. In FIG. 7, portions correspondingto those in FIG. 6 are expressed by the same symbols and descriptions ofthem will be omitted.

[0148] This embodiment differs from the second embodiment shown in FIG.6 in that the power value calculating circuit 42 is removed and thatoutput from the power value calculating circuit 23 is provided to thelevel measuring circuit 41. Except for this, the structure of thisembodiment is the same as that of the second embodiment.

[0149] The power value calculating circuit 23 calculates the geometricmean of data output from the integrating circuit 22 and provides it tothe integrating circuit 24 and level measuring circuit 41.

[0150] The power value calculating circuit 42 shown in FIG. 6 performsthe process of calculating the geometric mean of data output from thememory 60. This process is the same as that performed by the power valuecalculating circuit 23. That is to say, the power value calculatingcircuit 23 can also be used as the power value calculating circuit 42.Therefore, in the third embodiment of the present invention, the powervalue calculating circuit 42 is removed.

[0151] Operation in the third embodiment is the same as that in thesecond embodiment, except that the power value calculating circuit 23calculates a power value on the basis of data for the power valuecalculating circuit 42. Detailed descriptions of it therefore will beomitted.

[0152] The above embodiment enables the path tracking section 20 anddata demodulating section 30 to share the power value calculatingcircuit 23. As a result, the size of circuits can be reduced further.

[0153] The path tracking section 20 and data demodulating section 30shown in the above embodiments can be semiconductor devices. Inaddition, these semiconductor devices can include their peripheralcircuits, such as the A/D converting circuit 12, RAKE combining circuit40, or level measuring circuit 41.

[0154] As has been described in the foregoing, a receiving unit forreceiving signals sent from a base station and demodulating the signals,according to the present invention, comprises receiving means forreceiving signals sent from the base station and transmitted through aplurality of paths, path tracking means for detecting timing of each ofthe plurality of paths through which the signals received by thereceiving means were transmitted, demodulating means for demodulatingthe received signals by performing a despreading process according tothe timing of the plurality of paths detected by the path trackingmeans, correlation value calculating means for calculating a correlationvalue between the received signals and a spreading code, and destinationselecting means for providing output from the correlation valuecalculating means to the path tracking means in the case of performing apath tracking process by the path tracking means and for providingoutput from the correlation value calculating means to the demodulatingmeans in the case of demodulating the received signals by thedemodulating means. As a result, the correlation value calculating meansis shared by dividing time and the size of circuits can be reduced.

[0155] The foregoing is considered as illustrative only of theprinciples of the present invention. Further, since numerousmodifications and changes will readily occur to those skilled in theart, it is not desired to limit the invention to the exact constructionand applications shown and described, and accordingly, all suitablemodifications and equivalents may be regarded as falling within thescope of the invention in the appended claims and their equivalents.

What is claimed is:
 1. A receiving unit for receiving and demodulatingsignals sent from a base station, the receiving unit comprising: areceiving section for receiving signals sent from the base station andtransmitted through a plurality of paths; a path tracking section fordetecting timing of each of the plurality of paths through which thesignals received by the receiving section were transmitted; ademodulating section for demodulating the received signals by performinga despreading process according to the timing of the plurality of pathsdetected by the path tracking section; a correlation value calculatingsection for calculating a correlation value between the received signalsand a spreading code; and a destination selecting section for providingoutput from the correlation value calculating section to the pathtracking section in the case of performing a path tracking process bythe path tracking section and for providing output from the correlationvalue calculating section to the demodulating section in the case ofdemodulating the received signals by the demodulating section.
 2. Thereceiving unit according to claim 1, further comprising a levelmeasuring section for referring to signals demodulated by thedemodulating section and measuring a level of the received signals. 3.The receiving unit according to claim 2, wherein the path trackingsection includes an integrating section for integrating the output fromthe correlation value calculating section, further wherein the levelmeasuring section measures the level of the received signals based onoutput from the integrating section.
 4. The receiving unit according toclaim 3, wherein the path tracking section includes a power calculatingsection for calculating power of the received signals based on theoutput from the integrating section, further wherein the level measuringsection refers to the output from the integrating section and outputfrom the power calculating section and measures the level of thereceived signals.
 5. The receiving unit according to claim 2, whereinthe level measuring section measures the level of the received signalsby RAKE combining.
 6. The receiving unit according to claim 1, whereinthe destination selecting section provides the output from thecorrelation value calculating section to the path tracking section in apredetermined cycle.
 7. The receiving unit according to claim 6, whereinthe predetermined cycle is changed properly according to relationbetween the receiving unit and the base station.
 8. The receiving unitaccording to claim 1, wherein the correlation value calculating sectionis a matched filter.
 9. The receiving unit according to claim 1, furthercomprising a path selecting section for selecting data corresponding toa desired path based on the output from the correlation valuecalculating section and providing the data to the demodulating section.10. The receiving unit according to claim 9, wherein the path selectingsection temporarily stores data output from the correlation valuecalculating section in a semiconductor memory and selects the desiredpath by reading out data from an address corresponding to the desiredpath supplied from the path tracking section.
 11. A receiving method forreceiving and demodulating signals sent from a base station, thereceiving method comprising: a receiving step for receiving signals sentfrom the base station and transmitted through a plurality of paths; apath tracking step for detecting timing of each of the plurality ofpaths through which the signals received by the receiving step weretransmitted; a demodulating step for demodulating the received signalsby performing a despreading process according to the timing of theplurality of paths detected by the path tracking step; a correlationvalue calculating step for calculating a correlation value between thereceived signals and a spreading code; and a destination selecting stepfor providing output from the correlation value calculating step toinput in the path tracking step in the case of performing a pathtracking process by the path tracking step and for providing output fromthe correlation value calculating step to input in the demodulating stepin the case of demodulating the received signals by the demodulatingstep.
 12. A semiconductor device for processing signals sent from a basestation, the semiconductor device comprising: a path tracking sectionfor detecting timing of each of a plurality of paths through whichsignals were received; a demodulating section for demodulating thereceived signals into an original data by performing a despreadingprocess according to the timing of the plurality of paths detected bythe path tracking section; a correlation value calculating section forcalculating a correlation value between the received signals and aspreading code; and a destination selecting section for providing outputfrom the correlation value calculating section to the path trackingsection in the case of performing a path tracking process by the pathtracking section and for providing output from the correlation valuecalculating section to the demodulating section in the case ofdemodulating the received signals by the demodulating section.
 13. Thesemiconductor device according to claim 12, further comprising a levelmeasuring section for referring to signals demodulated by thedemodulating section and measuring a level of the received signals. 14.The semiconductor device according to claim 13, wherein the pathtracking section includes an integrating section for integrating theoutput from the correlation value calculating section, further whereinthe level measuring section measures the level of the received signalsbased on output from the integrating section.
 15. The semiconductordevice according to claim 14, wherein the path tracking section includesa power calculating section for calculating power of the receivedsignals based on the output from the integrating section, furtherwherein the level measuring section refers to the output from theintegrating section and output from the power calculating section andmeasures the level of the received signals.
 16. The semiconductor deviceaccording to claim 13, wherein the level measuring section measures thelevel of the received signals by RAKE combining.
 17. The semiconductordevice according to claim 12, wherein the destination selecting sectionprovides the output from the correlation value calculating section tothe path tracking section in a predetermined cycle.
 18. Thesemiconductor device according to claim 17, wherein the predeterminedcycle is changed properly according to relation between the receivingunit and the base station.
 19. The semiconductor device according toclaim 12, wherein the correlation value calculating section is a matchedfilter.
 20. The semiconductor device according to claim 12, furthercomprising a path selecting section for selecting data corresponding toa desired path based on the output from the correlation valuecalculating section and providing the data to the demodulating section.21. The semiconductor device according to claim 20, wherein the pathselecting section temporarily stores data output from the correlationvalue calculating section in a semiconductor memory and selects thedesired path by reading out data from an address corresponding to thedesired path supplied from the path tracking section.